1. Field of the Invention
The present invention relates to optically active compounds, their preparation and their use for resolving racemates of optically active amino-compounds into individual optical isomers.
2. Description of the Prior Art
Several optically active acids are known which can be used as resolving agents for racemates of optically active amino-compounds, including amino-acids, which are used as intermediates for the preparation of pharmaceuticals. U.S. Pat. No. 3,848,030 describes such optically active acids. More particularly, the optically active acids disclosed in this patent are symmetrical around the acid group. Conversely, optically active amino-compounds can be used for separating specific racemates of optically active acids. Some examples of optically active amino-compounds are phenylglycine, para-hydroxyphenylglycine, 2-amino-1-butanol and 2-amino-1-phenyl-1,3-propanediol.
Optically active acids, however, are expensive and, typically, are prepared by a complex process. Moreover, these optically active resolving agents are not always resistant to racemization in an acidic or alkaline medium and they are often difficult to recover after use. Also, they generally are suitable only for separating a small number of racemates of optically active amino-compounds. For these reasons, attempts are continually being made to develop optically active acids without the above disadvantages.